I would recommend getting a good handle on the fundamentals of JavaScript first. Not just being able to fudge stuff together but actually understand closures, scope, the `this` keyword and how it behaves. Prototypes and object mixins, Ecmascript 6, promises, generators etc.
There is a really good set of little books called "you don't know js" which covers all this stuff. A lot of the newer frameworks are built around the new abilities of ec6 so there is not quite so much "magic" under the hood which means that a good grounding in JS will do you more good than ever before.
React is indeed flavour of the month at the moment but honestly if you want to learn jquery it's super simple. Some people suggest that it's inefficient but the speed and quality of JavaScript engines these days is amazing. Yes you can write awful jquery code but that's probably not due to a lack of knowledge of jquery but poor implementation of an idea that you would still have made a hash of in pure js.
The JavaScript engines in modern browsers optimise so much that a lot of traditional good practices are irrelevant because the engine will automatically do it for you.